Mechanical force-driven tunability of depletion, accumulation, and inversion modes in Bilayer ITO–PVDF-TrFE Piezo-gated flexible field-effect transistors

Emerging fields such as wearable technolog, pervasive computing, industrial automation, and human–machine interfaces demand electronics capable of actively and adaptively interacting with their environment. Addressing these challenges requires solutions that offer low energy consumption, high efficiency, and flexibility. Herein, we report the development of a piezo-gated flexible field-effect transistor (PGFFT) that utilizes the piezoelectric properties of PVDF-TrFE, replacing an electric gate, where the PVDF-TrFE was polarized via corona poling. In our PGFFT designs, n-type indium tin oxide (ITO) served as the channel material, was positioned on either the positively charged side (ITO-P) or the negatively charged side (ITO-N) of the PVDF-TrFE. Under compressive stress, the ITO-P device exhibited first a decrease in drain current due to electron depletion turning to an increase at even higher compressive stresses due to charge inversion, while the ITO-N device showed an increase in drain current owing to electron accumulation in the channel. Notably, we are the first to demonstrate piezo-gating transistor inversion mode, enabling a transition from electron- to hole-dominated conduction in a piezo-gated transistor. This achievement paves the way for new possibilities in flexible electronics by operating piezo-gated devices in inversion mode.